In the last decades, attempts have been increasingly made to treat biomass by enzymatic digestion (see, for example, DE-A-19845207). Thus, today, a number of approaches exist in which purified enzymes or enzyme mixtures or other enzyme-producing microbial pure or mixed cultures are employed for treating biological substrates. Examples include the treatment of wood chops in the course of biopulping, the treatment of annual plants for improving the properties as a fodder or of bagasse for preparing bioalcohol. However, all these processes still have a less than optimum course. The main reason thereof is that the enzyme mixtures, microorganism cultures or microorganism mixed cultures employed are not optimally adapted to the target substrates (e.g., the organisms and enzymes are not optimally adapted to and selected for cold to very cold locations), which results in very long treatment times of the chops, for example, in biopulping, with corresponding great space requirements for the stack areas.
Many biotechnological processes for the treatment of complex substrates (mostly plant material, but also animal waste from slaughterhouses etc.) often additionally require particular cofactors, e.g. specific tailor-made accompanying enzymes or mediators, which are in part still unknown, in addition to the known enzyme mixtures (hydrolases, oxidoreductases) for a possibly extensive degradation (mainly for oxidoreductases). This means that single enzymes or even additions of mixtures to the process are only conditionally successful because only a cooperation of enzyme mixtures previously adapted to and optimized for the target substrates together with these additional factors can show an optimum performance. However, to date, this has not been possible in an optimum way either.
From DE-A-3539875, for example, a method and a device for the continuous preparation of an enzyme mixture for the treatment of biomass in biogas plants have been known. However, a pure culture of Aspergillus niger is employed without induction of this culture by the plant substrates later used for the methanization. Therefore, it cannot be expected that the enzyme mixture formed thereby is optimally adapted to the biomass-utilizing process.
Defined enzyme mixtures and/or metabolite mixtures which are optimally adapted to a complex biological substrate can be produced only by exerting a selection pressure on the producing microorganism populations (mixed cultures) and/or their induction by the corresponding target substrates.
Now, it is generally known that the application of a selection pressure to mixed populations of microorganisms by adjusting defined environment parameters in the course of the culturing of these organisms usually leads to particular population spectra. However, these population spectra are non-directed and random.
It is also known that particular species of microorganisms can be enriched or contaminants suppressed by selecting the culture conditions.
It is also known that metabolite spectra which vary in time can occur during the course of such cultures as a function of the selection conditions chosen, but also as a function of the nature of the substrate and the availability of inducers (for non-constitutively formed proteins and metabolites). However, these metabolite spectra are also non-directed and random.
Methods of the type mentioned are employed, for example, on defined solid substrates (agar plates→mutagenesis treatments, genetic transformations etc.) and in the field of the submerged culture technique (in the form of chemostats or turbidostats also continuously). In the latter case, the cultures are mainly pure cultures for achieving specific metabolic performances.
Bioreactors for the continuous reaction of solid substrates are known from different fields of application (food technology, composting technology etc.). For example, the fermentation matter is conveyed through rolls in composting plants. However, such methods do not allow for a demanding regulation of the culturing parameters. For example, the use of one or more conveying screws in solid-phase bioreactors has been known from DE-A-10041977, DE-A-4308920 and DE-A-4208920. However, these bioreactors do not have a modular design and also fail to provide a possibility of a later addition of substrates and other substances, for example, for induction. Although the bioreactor mentioned in DE-A-100 29 668 is a segment screw conveyor, in contrast to the reactor according to the invention, it cannot utilize the time-dependence of the quantitative or qualitative production of the enzyme mixtures as a control variable for a feedback control of the running process itself, but also for the downstream target processes, i.e., it does not possess adjusting options and control of pH and moisture as a preferred property according to the invention, it cannot be optionally sterilized, and in particular, it also fails to possess a possibility for the metered addition of substrates, target substrates, inducers, inhibitors etc. according to the invention, and it fails to possess possibilities of inoculating and withdrawing growth-supporting enzyme-containing substrate during the initial growth process and the enzyme forming process.